This invention relates to the field of resource reservation, and in particular to a method of controlling access to a communications network, and to components of a network using such a method.
The Internet is a communications network which is becoming widely available. The Internet provides a xe2x80x9cbest effortxe2x80x9d bearer service. That is, the user receives the best service available at the time he requests it, but no commitments are given to the user in terms of available bandwidth, transit delay, or packet loss. The Internet is particularly useful in data communications applications, but is of limited use for telecommunications applications which require guaranteed bandwidth availability, and specify maximum values for the transit delay and loss of data. The Internet cannot usually guarantee the required quality of service.
One conventional way of achieving resource reservation, to be able to provide a required quality of service commitment, is to use connection states to store information in the network nodes about bandwidth, buffer parameters, connection identity and status. However, an advantage of the Internet is that it is a connectionless network, which therefore cannot use this technique without sacrificing the simplicity of the Internet.
One conventional way of achieving bearer service differentiation, in a connectionless network, is to use a set of priority bits in the packet header. However, in a public connectionless network, it is still necessary to control how many connections use the highest available priority. If every connection uses the highest available priority, the network can still in effect only offer a best effort service to the users.
A problem remains, therefore, as to how to control admission to the network.
The present invention seeks to solve the problem of achieving admission control and resource reservation in a connectionless network.
According to the invention, each transmission by a user across the network includes a message sent to the user from the network. The message includes information about the priority level of the transmission, based on the user""s contract with the network provider, and can subsequently be extracted by the network to determine how to handle the transmission.
Thus, rather than rely on the network being able to detect the status of the connection, the relevant information is transmitted by the user with the data transmission, and can be extracted by the network as required.
In preferred embodiments, this information can be used for admission control and for routing purposes.
For a better understanding of the present invention, and to show how it may be brought into effect, reference will now be made, by way of example, to the accompanying drawings.